1) The document describes upgrading an Oracle Grid Infrastructure installation from 12.1.0.1 to 12.1.0.2. There were issues with the rootupgrade script, but moving the ASM SPFILE location resolved it.
2) Key steps included running the Grid Infrastructure 12.1.0.2 installation, applying the PSU patch 19791375, and verifying the services started up successfully from the new Oracle home.
3) Applying the latest OPatch version 12.1.0.1.5 prior to installing the PSU is also documented.